Not from the industry, are you, Andrew Mike and John.
Ever tried running an old car? Eventually there are so many failing bits that it just isn't worth the effort, assuming you have the option to replace it with something.
I have been involved in such a project. As the gas flame is non-luminous, (coal being luminous) it causes major problems with the heat transfer. To the point of eventually destroying the boiler without major modifications. I suppose if you derated the boiler you might get away with it.
Yes. We tried ceramic "targets" in the path of the flame. Not very successful.
We took had taken out a boiler that was absolutely shagged. I thought they'd cut it up on site, but no. Carefully removed.
They'd sold it to some place in Pakistan.
In fact that's merely marginally accidental. Both need decent supplies of cooling somehow, and it turns out that transporting uranium by sea upsets less shrinking violets.
Drax uses the Ouse for cooling purposes. many nukes in France are on Rivers.
For a given power a conventional steam turbine needs the same amount of coolant whatever heat source feeds its boilers.
Some are, some arent, And they can be refurbed
Cost benefit rules, BUT its more akin top repairing a classic car. remember every power station is a 'one off' so mass production only goes so far top bring the costs down. To refurb an old boiler is often cheaper than building a new one.
Same goes for condensers and alternators. Maybe the steam turbines get replaced now and again.
Nukes die from neutron bombardment eventually, at that point they are truly beyond repair.
Well I suppose you can refurbish anything at a price. I agree it comes down to cost benefit. It's sometimes worth reblading steam turbines, in part because new manufacturing processes and CFD let you push the efficiency. But it is not just "big lumps" in a thermal power station. There's lots of pipework, valves, pumps, heat exchangers, and C&I. If you have a car with rotten bodywork it is not (generally) worth getting a new shell and transferring over not only the engine and transmission, but the wiring, plumbing, hydraulics, glass, trim, etc.
If you are moving from coal to gas, the sensible thing is to go to CCGT and the old T/A set is simply not re-useable.
It's not only the neutron flux which degrades nuclear plant, there are also thermal ageing processes, not to mention accumulation of creep and fatigue damage. And all of these processes apply to parts of coal fired plant too.
And IIRC some "nuke" pressure vessels (overseas) have been annealed to reduce the effects of radiation embrittlement.
En el artículo , newshound escribió:
I read an interesting article recently that said material wear/fatiguing/embrittlement has to be treated differently in a nuclear environment because of the intense radiation causing subtle changes in the atomic structure of materials.
I've had a hunt and can't find it again, but this Wonkypedia page covers the basics:
All true, but the doses to materials are not all that high in UK gas cooled reactors. Gamma doses are much higher in parts of the Sellafield reprocessing plant, for example. Neutron doses are higher in PWR pressure vessels, and very much higher in fast reactor internals, and also in fusion research facilities.
They are regularly taken into account in safety cases, but so are thermal ageing, creep, and fatigue.
Trawsfynydd was shut down early because of concerns over irradiation embrittlement to welds, but the general view afterwards (and after assessing more experimental data) was that this decision had been unnecessarily cautious.
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